The present invention relates to a ceramic bearing comprising an inner ring, an outer ring, and a plurality of rolling elements rollably arranged between said inner and outer rings all made of ceramics (a sintered compact mainly composed of silicon nitride or Sialon).
A type of ceramics bearing comprising an inner ring, an outer ring, and a plurality of rolling elements all made of ceramics is called "entire ceramics bearing". When a bearing is provided with a retainer for the rolling elements, the retainer may not be composed of ceramics. In the conventional entire ceramics bearing, the characterics of the ceramics of the inner ring, the outer ring, and the rolling elements are controlled the same, so as to afford a suitable ceramics bearing.
However, the conventional entire ceramics bearing is not suitable for, for example, a diesel engine because the bearing of the diesel engine is used at high temperature and high speed, so that the bearing cannot resist a load and its lifetime is rather short. So long as the entire ceramics bearing comprises the inner ring, the outer ring and the rolling elements with the same material characterics, the rolling elements may exfoliate and fracture rather earlier when used at the high temperature and high speed. In developing the materials of the ceramics, there are considered the density, the thermal conductivity, the special heat, the bearing strength, the compressive strength, the coefficient of line extension, the longitudinal modulus of elasticity, and so on. However, the various considerations may be very complex and are not suitable for the elementary criteria of determination.